Hadoop学习---第四篇Mapreducer里的Partitioner

Partitioner就是对map输出的key进行分组，不同的组可以指定不同的reduce task处理；

Partition功能由partitioner的实现子类来实现

每写一段代码都会加深理解，程序里记录了自己的理解

FlowBean类源码：

package cn.zxl.flowcountpartitioner;import java.io.DataInput;import java.io.DataOutput;import java.io.IOException;import org.apache.hadoop.io.WritableComparable;public class FlowBean implements WritableComparable<FlowBean>{private long upflow;//上行流量private long downflow;//下行流量private long sumflow;//总流量public long getUpflow() {return upflow;}public void setUpflow(long upflow) {this.upflow = upflow;}public long getDownflow() {return downflow;}public void setDownflow(long downflow) {this.downflow = downflow;}public long getSumflow() {return sumflow;}public void setSumflow(long sumflow) {this.sumflow = sumflow;}public FlowBean() {}public FlowBean(long upflow, long downflow) {super();this.upflow = upflow;this.downflow = downflow;this.sumflow = upflow+downflow;}@Overridepublic void readFields(DataInput in) throws IOException {upflow=in.readLong();downflow=in.readLong();sumflow=in.readLong();}@Overridepublic void write(DataOutput out) throws IOException {out.writeLong(upflow);out.writeLong(downflow);out.writeLong(sumflow);}@Overridepublic int compareTo(FlowBean bean) {return sumflow>bean.getSumflow()?-1:1;}@Overridepublic String toString() {return upflow+"\t"+downflow+"\t"+sumflow;}}

ProvicePartition类源码：

package cn.zxl.flowcountpartitioner;import java.util.HashMap;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Partitioner;public class ProvicePartition extends Partitioner<Text, FlowBean>{//根据手机号前三位划分分组//Partitioner就是对key进行分组private static HashMap<String, Integer> pmap = new HashMap<String, Integer>();static{pmap.put("136", 0);pmap.put("137", 1);pmap.put("138", 2);pmap.put("139", 3);}@Overridepublic int getPartition(Text key, FlowBean bean, int numPartitions) {String prex=key.toString().substring(0,3);Integer partNum=pmap.get(prex);//根据key截取的前三位做key和map的值是否匹配return partNum==null?4:partNum;}}

FlowCount类源码：

package cn.zxl.flowcountpartitioner;import java.io.IOException;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;public class FlowCount {static class FlowCountMapper extends Mapper<LongWritable, Text, Text, FlowBean>{@Overrideprotected void map(LongWritable key, Text value,Context context)throws IOException, InterruptedException {String line=value.toString();String[] phoneinfo=line.split("\t");String phoneN=phoneinfo[0];String upflow=phoneinfo[phoneinfo.length-3];String downflow=phoneinfo[phoneinfo.length-2];FlowBean fb=new FlowBean(Long.parseLong(upflow),Long.parseLong(downflow));context.write(new Text(phoneN),fb);}}//reducer里的值是<key,list(value)>,也就是相同的键里对应一个集合//reducer是根据key排序的，而不是value,要根据什么排序，那就得已什么作为key输出static class FlowCountReducer extends Reducer<Text, FlowBean, Text, FlowBean>{@Overrideprotected void reduce(Text key, Iterable<FlowBean> values,Context context)throws IOException, InterruptedException {long upflow_sum=0;long downflow_sum=0;for(FlowBean bean:values){upflow_sum+=bean.getUpflow();downflow_sum+=bean.getDownflow();}FlowBean fb=new FlowBean(upflow_sum,downflow_sum);context.write(new Text(key), fb);}}public static void main(String[] args) throws Exception {Configuration conf=new Configuration();// cn.zxl.flowcountpartitioner.FlowCountJob job=Job.getInstance(conf);job.setJarByClass(FlowCount.class);job.setMapperClass(FlowCountMapper.class);job.setReducerClass(FlowCountReducer.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(FlowBean.class);//job指定自定义的Partitioner组件//job.setPartitionerClass(ProvicePartition.class);/*job中指定reducertask的数量,说明：这里的reducertask数量可以指定为1个，如果是1个reducertask，*那么所有的分区数据都输入到一个文件里，如果指定个数小于分区个数(这里是5个)，那么程序会报错，*因为不知道对应的一个分区数据放置到哪里，如果指定个数超过分区个数，那么后面产生的文件是空的*///job.setNumReduceTasks(5);FileInputFormat.setInputPaths(job, new Path(args[0]));Path output = new Path(args[1]);FileSystem fs = output.getFileSystem(conf);//看输出是否存在，存在就删除，特别说明：安全起见正式的线上建议最好不要做这个判断，如果这样做，会把以前产生的数据删除//补充：正式生产环境最好指定删除多久后正式删除数据，以便错删时可以恢复数据/* * 添加在hdfs-site的配置文件里 * <property><name>fs.trash.interval</name><value>60</value><!-- 回收站过期机制检查频率（分钟） --></property><property><name>fs.trash.checkpoint.interval</name><value>20</value><!-- 回收站中文件过期的时间限制（分钟） --></property> */if(fs.exists(output)){fs.delete(output, true);}FileOutputFormat.setOutputPath(job, new Path(args[1]));job.waitForCompletion(true);}}

测试数据：

1363157985066 1372623050300-FD-07-A4-72-B8:CMCC120.196.100.82i02.c.aliimg.com2427 248124681 200
1363157995052 138265441015C-0E-8B-C7-F1-E0:CMCC120.197.40.440 264 0 200
1363157991076 1392643565620-10-7A-28-CC-0A:CMCC120.196.100.9924 132 1512 200
1363154400022 139262511065C-0E-8B-8B-B1-50:CMCC120.197.40.440 240 0 200
1363157993044 1821157596194-71-AC-CD-E6-18:CMCC-EASY120.196.100.99iface.qiyi.com视频网站15 12 1527 2106 200
1363157995074 841384135C-0E-8B-8C-E8-20:7DaysInn120.197.40.4122.72.52.122016 41161432 200
1363157993055 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
1363157995033 159201332575C-0E-8B-C7-BA-20:CMCC120.197.40.4sug.so.360.cn信息安全20 20 3156 2936 200
1363157983019 1371919941968-A1-B7-03-07-B1:CMCC-EASY120.196.100.8240 240 0 200
1363157984041 136605779915C-0E-8B-92-5C-20:CMCC-EASY120.197.40.4s19.cnzz.com站点统计24 9 6960 690 200
1363157973098 150136858585C-0E-8B-C7-F7-90:CMCC120.197.40.4rank.ie.sogou.com搜索引擎28 27 3659 3538 200
1363157986029 15989002119E8-99-C4-4E-93-E0:CMCC-EASY120.196.100.99www.umeng.com站点统计3 3 1938 180 200
1363157992093 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.99159 918 4938 200
1363157986041 134802531045C-0E-8B-C7-FC-80:CMCC-EASY120.197.40.433 180 180 200
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1363157995093 1392231446600-FD-07-A2-EC-BA:CMCC120.196.100.82img.qfc.cn1212 30083720 200
1363157982040 135024688235C-0A-5B-6A-0B-D4:CMCC-EASY120.196.100.99y0.ifengimg.com综合门户57 102 7335 110349 200
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1363157990043 1392505741300-1F-64-E1-E6-9A:CMCC120.196.100.55t3.baidu.com搜索引擎69 63 11058 48243 200
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1363157993055 13560436666C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
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1373157991076 1392643565620-10-7A-28-CC-0A:CMCC120.196.100.9924 132 1512 200
1373154400022 139262511065C-0E-8B-8B-B1-50:CMCC120.197.40.440 240 0 200
1373157993044 1821157596194-71-AC-CD-E6-18:CMCC-EASY120.196.100.99iface.qiyi.com视频网站15 12 1527 2106 200
1373157995074 841384135C-0E-8B-8C-E8-20:7DaysInn120.197.40.4122.72.52.122016 41161432 200
1373157993055 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
1373157995033 159201332575C-0E-8B-C7-BA-20:CMCC120.197.40.4sug.so.360.cn信息安全20 20 3156 2936 200
1373157983019 1371919941968-A1-B7-03-07-B1:CMCC-EASY120.196.100.8240 240 0 200
1373157984041 136605779915C-0E-8B-92-5C-20:CMCC-EASY120.197.40.4s19.cnzz.com站点统计24 9 6960 690 200
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1373157992093 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.99159 918 4938 200
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1373157993055 13560436666C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
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1383154400022 139262511065C-0E-8B-8B-B1-50:CMCC120.197.40.440 240 0 200
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1383157995074 841384135C-0E-8B-8C-E8-20:7DaysInn120.197.40.4122.72.52.122016 41161432 200
1383157993055 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
1383157995033 159201332575C-0E-8B-C7-BA-20:CMCC120.197.40.4sug.so.360.cn信息安全20 20 3156 2936 200
1383157983019 1371919941968-A1-B7-03-07-B1:CMCC-EASY120.196.100.8240 240 0 200
1383157984041 136605779915C-0E-8B-92-5C-20:CMCC-EASY120.197.40.4s19.cnzz.com站点统计24 9 6960 690 200
1383157973098 150136858585C-0E-8B-C7-F7-90:CMCC120.197.40.4rank.ie.sogou.com搜索引擎28 27 3659 3538 200
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1383157992093 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.99159 918 4938 200
1383157986041 134802531045C-0E-8B-C7-FC-80:CMCC-EASY120.197.40.433 180 180 200
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1393157995033 159201332575C-0E-8B-C7-BA-20:CMCC120.197.40.4sug.so.360.cn信息安全20 20 3156 2936 200
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1393157984041 136605779915C-0E-8B-92-5C-20:CMCC-EASY120.197.40.4s19.cnzz.com站点统计24 9 6960 690 200
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1393157993055 13560436666C4-17-FE-BA-DE-D9:CMCC120.196.100.991815 1116954 200
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1513157995074 841384135C-0E-8B-8C-E8-20:7DaysInn120.197.40.4122.72.52.122016 41161432 200
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1513157995033 159201332575C-0E-8B-C7-BA-20:CMCC120.197.40.4sug.so.360.cn信息安全20 20 3156 2936 200
1513157983019 1371919941968-A1-B7-03-07-B1:CMCC-EASY120.196.100.8240 240 0 200
1513157984041 136605779915C-0E-8B-92-5C-20:CMCC-EASY120.197.40.4s19.cnzz.com站点统计24 9 6960 690 200
1523157973098 150136858585C-0E-8B-C7-F7-90:CMCC120.197.40.4rank.ie.sogou.com搜索引擎28 27 3659 3538 200
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1523157992093 13560439658C4-17-FE-BA-DE-D9:CMCC120.196.100.99159 918 4938 200
1523157986041 134802531045C-0E-8B-C7-FC-80:CMCC-EASY120.197.40.433 180 180 200
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